CN109477511B

CN109477511B - Integrated journal bearing

Info

Publication number: CN109477511B
Application number: CN201780043844.6A
Authority: CN
Inventors: 艾利·厄尔-舍费
Original assignee: Individual
Current assignee: Individual
Priority date: 2016-05-17
Filing date: 2017-05-17
Publication date: 2020-08-18
Anticipated expiration: 2037-05-17
Also published as: IL262880B1; US10612592B2; EP3458733B1; IL300968A; EP3458733A4; US20170335888A1; US10954999B2; RU2018142320A3; ZA201808394B; IL262880A; US20190234461A1; BR112018073562A2; AU2021203888B2; KR102377184B1; IL262880B2; MA45049A; AU2021203888A1; KR20190008340A; RU2725842C2; WO2017201151A1

Abstract

An Integrated Journal Bearing (IJB), comprising: a shaft extending in an axial direction; a housing through which the shaft extends in the axial direction, the housing surrounding the shaft in a radial direction; an Active Magnetic Bearing (AMB) arranged within the housing and surrounding the shaft in the radial direction; and at least one first fluid film Journal Bearing (JB) arranged within the housing and surrounding the shaft in the radial direction. The first JB is axially adjacent to the AMB such that the first JB and the AMB do not share a common radial gap, while the first fluid film journal bearing and the active magnetic bearing are collectively oil-immersed. A controller in signal communication with the AMB may be variously configured to supply current to the active magnetic bearing to operate the AMB by controlling the magnetic force generated by the active magnetic bearing.

Description

Integrated journal bearing

Cross Reference to Related Applications

This application claims priority to U.S. provisional patent application No. 62/337,555, filed 2016, 5, 17, the entire contents of which are incorporated herein by reference in their entirety.

Technical Field

The present invention relates to journal bearings, and more particularly to journal bearings that integrate both fluid films and magnetic load bearing elements.

Background

Fluid Film Bearings (FFB) and Active Magnetic Bearings (AMB) are competitive devices in the market. FFB, and in particular Journal Bearings (JB), are excellent load bearing elements due to their large load bearing capacity and their ability to introduce passive damping into the rotor system. However, JBs exhibit unstable oscillations at high speeds, known as oil film oscillations, which are excited when the rotor speed reaches about twice the first critical speed. This instability limits the possibility of increasing the rotational speed of the rotor.

AMBs, on the other hand, provide non-contact rotor support at high speeds and are free of oscillatory instability. An additional feature of the active magnetic bearing is its ability to act as a control element. AMBs can provide variable and controllable stiffness and damping, and additionally can provide unbalanced control and many other control features. However, AMBs have certain disadvantages.

Reliability issues in particular have been a concern for AMB designers. In practice, AMBs are always designed with redundant bearing systems, known as "back-up bearings", so that in the event of a failure of the AMB, the rotor is carried by the back-up bearings.

Disclosure of Invention

In view of the above, the main objective of the present invention is to provide a method for producing a light emitting diode

The present invention provides an intelligent high performance integrated bearing that combines a Fluid Film Bearing (FFB) and an electromagnetic actuator (EMA) in one integrated device. In all cases, the fluid film bearing should carry the load, while the electromagnetic actuator may be used as a pure controller or as both a controller and a load carrying element. In the latter case, the electromagnetic actuator may be considered as an Active Magnetic Bearing (AMB).

The integration of AMBs and JBs in one device, referred to herein as an Integrated Journal Bearing (IJB), has significant advantages. IJB has all the advantages of JBs and AMBs, and avoids all the disadvantages of AMBs and JBs. IJB is an excellent load carrying element due to its greater load carrying capacity and its ability to introduce passive damping into the rotor system. Furthermore, the integrated journal bearing has no oscillatory instability and has the ability to act as a controller. IJB may provide variable and controllable stiffness and damping, and in addition may provide unbalanced control and many other control features. Most importantly, no back-up bearings are required since the rotor is carried on the JB in all cases.

Accordingly, it is a general object of the present invention to provide an improved bearing for rotating a machine.

It is a further object of the present invention to provide a fluid film bearing integrated with an electromagnetic actuator that is confined in one space.

It is another object of the present invention to provide a fluid film bearing integrated with an electromagnetic actuator confined in an oil filled space.

It is a further object of the present invention to provide an electromagnetic actuator within the integrated bearing that functions as an active magnetic bearing.

It is a further object of the present invention to provide an active magnetic bearing within the integrated bearing that may or may not carry loads.

A particular object of the invention is to provide an excellent load carrying element.

An additional object of the present invention is to provide a load bearing member having excellent load bearing capacity.

It is another object of the present invention to provide a load bearing member that can introduce passive damping into the rotor system.

It is a further object of the present invention to provide a load bearing member that is free of oscillatory instability.

It is a further object of the present invention to provide a load bearing member that can be used as a controller.

It is a further object of the present invention to provide a load carrying member that can provide variable and controllable stiffness and damping.

It is an additional object of the present invention to provide a load bearing member that can provide unbalanced control.

It is an additional object of the present invention to provide a load bearing member that can provide a number of active control features.

It is a further additional object of the present invention to provide an excellent load bearing member that can provide all of the above features without the need for a backup bearing.

Advantageously, the integrated journal bearing according to the present invention can achieve all of the above objectives simultaneously.

In a preferred embodiment, the magnetic bearing surrounds the laminated rotor and maintains its own proper clearance. Two journals (possibly of the same diameter as the laminated rotor) fit on each side of the AMB and hold the rotor laminations in place. Two JBs are mounted with their own specific gap above the two journals. The oil conduit introduces oil into both JBs, allowing the oil to flow freely into the AMB space. Oil seals are used to seal the oil flow outside the integrated bearing.

This embodiment accomplishes the desired objectives in a unique manner. To maintain symmetry, two journal bearings surround the AMB in a confined space. Oil is introduced into the confined space, thus submerging both the AMB and the FFB. A controller is then used to control the AMB to achieve the desired performance.

In another embodiment, only one FFB and one AMB are used. In this embodiment, the magnetic bearing surrounds the laminated rotor and maintains its own proper clearance. Journals (possibly of the same diameter as the laminated rotor) fit alongside the AMB and hold the rotor laminations in place. The JBs are mounted over the journals with their own specific clearances. The oil conduit introduces oil into the JB, allowing the oil to flow freely into the AMB space. Oil seals are used to seal the oil flow outside the integrated bearing.

Other reasonable embodiments with two AMBs and one FFB are possible and it will be clear to the skilled person that the most suitable embodiment can be chosen for the specific application at hand.

It should be clear that for the purposes of this application, whether the FFB is a JB or oval bearing, or a pressure dam bearing or a multi-lobed bearing or even a pitched-shoe bearing. Similarly, whether AMB is a load-bearing AMB or only an EMA. The particular design and application area will dictate the type of FFB and AMB used.

The present inventors have demonstrated in their invention of us patent No. 7,836,601 in 2010 the possibility of integrating the FFB and AMB in one device. This is a significant breakthrough. Until that time, no one would consider adding oil on the magnetic bearing. In fact, the motivator of AMBs has liked it as an "oil-free" device, claiming that this is one of the advantages of AMBs. U.S. patent No. 7,836,601 is a mental paradigm shift for introducing oil into AMBs.

The specification of us patent No. 7,836,601 explains that an integrated bearing may be in the form of one integral bearing, in which a fluid film bearing is located within a magnetic bearing, such that fluid for the fluid film bearing passes through the rotor of the magnetic bearing and passes within the gap between the rotor and stator in the magnetic bearing.

However, design issues arise in this case as the magnetic bearings will require large clearances to dissipate the generated heat, while the fluid film bearings will require small clearances to improve load carrying capacity. This design problem can be solved in two ways, one is to choose a compromise gap between the two conflicting requirements, and the other is to use a small gap to load the fluid film bearing and increase the fluid flow in the magnetic bearing to dissipate the generated heat.

Similar to us patent No. 7,836,601, the present application considers FFB and AMB as integrated bearings, but unlike us patent No. 7,836,601, FFB and AMB do not share the same gap. In the present invention, the integrated bearing is composed of the AMB and the FFB integrated in one device, but not sharing the gap. However, both AMB and FFB are immersed in oil.

Us patent No. 7,836,601 demonstrates the advantages and disadvantages of the present invention which actually relies on two devices. The present invention uses fluid film bearings (whether cylindrical journal bearings, elliptical bearings, semi-offset bearings, multi-lobed bearings, or swashplate bearings) as the main load bearing bearings and uses magnetic bearings in combination with the fluid film bearings to control instability. This should be a very efficient combination which allows the bearing to be used at high speeds without stability or reliability problems.

Further, U.S. patent No. 7,836,601 cites a number of patents relating to magnetic bearings, such as:

6,737,777 magnetic bearings and their use;

6,727,617 method and apparatus for providing a triaxial magnetic bearing having permanent magnets mounted on radial poles;

6,720,695 rotor rotation device for a rotating rotor with a non-contact passive radial bearing;

6,717,311 Combined magnetic radial and thrust bearing;

6,707,200 Integrated magnetic bearing;

6,703,736 magnetic bearings;

6,653,756 magnetic bearing means; and

6,606,536 magnetic bearing device and magnetic bearing control device.

However, none of these patents discuss the use of magnetic bearings as a means of controlling journal bearing instability. Indeed, most of the state of the art and current development of magnetic bearings is directed towards using magnetic bearings as the primary load carrying element and using an over-control action to provide some of the desired stability benefits in the rotating machine.

Also, U.S. patent No. 7,836,601 cites a number of patents relating to fluid film bearings, such as:

6,089,756 a flat bearing;

5,879,085 a swashplate hydrodynamic bearing for rotating the machine;

5,795,076 a swashplate hydrodynamic bearing for rotating the machine;

5,772,334 fluid film bearings;

5,743,657 a shingle journal bearing;

5,743,654 hydrodynamic and actively controlled movable pad bearing;

5,634,723 hydrodynamic fluid film bearing;

5,549,392 shaft seal for a fluid dynamic bearing unit;

5,531,523 rotor journal bearing with adjustable bearing shoes;

5,516,212 fluid dynamic bearings with controlled lubricant pressure distribution;

5,489,155A variable geometry bearing of the tilting pad type having tilting pads and a method for manufacturing the same;

5,480,234 journal bearings;

5,322,371 fluid film bearings;

5,201,585 fluid film journal bearing for a turbocharger machine with squeeze film damper;

5,096,309 fluid dynamic bearing system;

5,032,028 fluid film bearings;

4,961,122 a hydrodynamic grooved bearing arrangement;

4,828,403 a resiliently mounted fluid bearing assembly;

4,880,320 fluid film journal bearing;

4,767,223 fluid dynamic journal bearing;

4,597,676 hybrid bearings;

4,526,483 fluid foil bearing;

4,415,281 hydrodynamic fluid film bearing;

4,300,808 a shingle bearing;

4,034,228 a shingle bearing; and

3,969,804 method of assembling a bearing housing for a high speed rotating shaft.

However, none of these patents suggest the use of magnetic bearings as a means of controlling fluid film instability.

In fact, the development of magnetic bearings and the development of fluid film bearings are two completely separate items, and researchers in both areas do not appreciate the development of the other area as if they were two distinct islands.

The exception is us patent No. 6,353,273, hybrid foil-magnetic bearings. In that invention, foil bearings and magnetic bearings are proposed for use as load carrying elements. It is possible to do so to carry a large load so that each of the foil bearing and the magnetic bearing carries a part of the load. However, that is not a good solution in the inventors' view. Although capable of operating at high speeds, hybrid foil-magnetic bearings still suffer from the same disadvantages as magnetic bearings.

Although fluid film bearings and magnetic bearings are well known devices, it is not obvious to use them in combination, as current technology makes them competitive rather than complementary devices. They are all considered load carrying devices with a certain control capability (passive control of the fluid film bearing and active control of the magnetic bearing). Thus, this is an invention in which the magnetic bearing is regarded only as a control device, and the fluid film bearing is regarded only as a load-carrying device. In addition to all the known advantages of fluid film bearings and magnetic bearings, the combined effect of magnetic bearings and fluid film bearings is to provide the bearings with the advantages of large load carrying capacity, excellent reliability, and no instability for use at high speeds. Furthermore, an additional advantage will arise that since the magnetic bearings do not act as load carrying elements, the power requirements will be reduced and thus smaller, lighter magnetic bearings capable of reliably controlling rotor vibrations can be used.

Drawings

In the drawings:

FIG. 1 is a cross-sectional elevation view of an embodiment of the present invention depicting an integrated journal bearing, wherein the magnetic bearing surrounds the laminated rotor and maintains its own proper clearance. Two journals (possibly of the same diameter as the laminated rotor) fit on each side of the AMB and hold the rotor laminations in place.

Fig. 2 is an exploded view of the embodiment shown in fig. 1, showing details of the components. This is an example established and tested by the inventors.

FIG. 3 is a cross-sectional elevation view of another embodiment of the present invention, depicting an integrated journal bearing, wherein the magnetic bearing surrounds the laminated rotor and maintains its own proper clearance, and the journal is assembled adjacent to the AMB and holds the rotor laminations in place.

Fig. 4 is an exploded view of the embodiment shown in fig. 3, showing details of the components.

FIG. 5 is a sectional elevation of yet another embodiment of the invention depicting an integrated journal bearing, wherein the magnetic bearing surrounds the laminated rotor and maintains its own proper clearance, and the journal is assembled adjacent to the AMB and holds the rotor laminations in place with alternate fasteners.

Fig. 6 is an exploded view of the embodiment shown in fig. 5, showing details of the components.

FIG. 7 shows the basic control circuit for controlling an active magnetic bearing with feedback from the rotor state including journal bearing characteristics.

Detailed Description

The present invention is an intelligent high performance integrated bearing that combines a Fluid Film Bearing (FFB) and an electromagnetic actuator (EMA) in one integrated device. In all cases, the fluid film bearing should carry the load, while the electromagnetic actuator may be used as a pure controller or as both a controller and a load carrying element. In the latter case, the electromagnetic actuator may be considered as an Active Magnetic Bearing (AMB).

Integrating the AMB and JB in one device, i.e. an integrated radial bearing (IJB), has significant advantages. IJB has all the advantages of JBs and AMBs, and avoids all the disadvantages of AMBs and JBs. IJB are excellent load bearing elements due to their greater load bearing capacity and their ability to introduce passive damping into the rotor system. Furthermore, the integrated radial bearing has no oscillation instability and has the ability to act as a controller. IJB may provide variable and controllable stiffness and damping, and additionally may provide unbalanced control and many other control features. Most importantly, no back-up bearings are required since the rotor is carried on the JB in all cases.

Fig. 1 and 2 show a preferred embodiment of IJB. In this embodiment, the AMB rotor laminations 40 are mounted on the shaft while the outer laminations 30 are held in place by IJB the lower and

upper housings

10, 60. The gap of the AMB is actually the gap between the rotor laminations 40 and the outer laminations 30. Two journal bearing sleeves 80 are placed on the rotor on either side of the rotor lamination 40. The journal bearing insert 70 is held in place around the sleeve 80 by the journal bearing housing 20, which is held in place by IJB the lower housing 10 and the upper housing 60. A journal bearing gap is located between the sleeve 80 and the liner 70. Oil is supplied and drained through conduit 120 and submerges both the journal bearing and the AMB chamber. The seal 50 prevents oil from escaping from the chamber. Two retaining sleeves 90 are used to hold the bearing sleeve 80 in place on the shaft. The fixing adapter 100 is locked on each holding sleeve 90 by a fixing nut 110.

Fig. 3 and 4 show another embodiment of IJB. In this embodiment, the AMB rotor laminations 180 are mounted on the shaft while the outer laminations 160 are held in place by the lower housing 140 and the upper housing 150 via IJB. The gap of the AMB is actually the gap between the rotor laminations 180 and the outer laminations 160. A journal bearing sleeve 190 is placed on the rotor next to the rotor laminations 180. The journal bearing liner 130 is held in place around the sleeve 190 by IJB the lower housing 140 and the upper housing 150. A journal bearing gap is located between the sleeve 190 and the liner 130. Oil is supplied and drained through conduit 210 and submerges both the journal bearing and the AMB chamber. A clamp 200 is used to hold the bearing sleeve 190 in place on the shaft. It should be noted that this embodiment is applicable to shafts having shoulders as shown in fig. 3, where the rotor laminations 180 rest against the shoulders and are held in place by journal sleeves 190, which in turn are held in place by clamps 200.

Fig. 5 and 6 show the same embodiment, but with different methods of fixing the rotor laminations and the journal sleeve. In fig. 5 and 6, AMB rotor laminations 230 are mounted on the shaft while outer laminations 270 are held in place by IJB lower and

upper shells

300 and 290. The gap of the AMB is actually the gap between the rotor laminations 230 and the outer laminations 270. A retainer sleeve 250 is used to retain the rotor laminations 270. The journal bearing sleeve 240 is inserted over the retainer sleeve 250 and held in place by the lock nut 260. The journal bearing liner 280 is held in place around the sleeve 240 by IJB the lower housing 300 and the upper housing 290. A journal bearing gap is located between the sleeve 240 and the liner 280. Oil is supplied and drained through conduit 320 and submerges both the journal bearing and the AMB chamber. This embodiment is also applicable to shafts having shoulders as shown in fig. 5, where the rotor laminations 230 rest against the shoulders and are held in place by retainer sleeve 250 and lock nut 260.

Fig. 7 shows a block diagram of IJB system. The rotor is subjected to an external force Fext, whereas the rotor states x and x' influence the JB, which in turn provides a bearing force Fb that is added to the magnetic bearing force Fm. The feedback states x and x' are electronically directed to a programmable controller that provides a current through a power amplifier to the AMB, thus creating a magnetic force Fm.

The inventors have applied a number of control algorithms similar to the block diagram in fig. 7. In reference 2, the inventor and his students discussed the use of IJB to control oil film oscillation through a number of algorithms, and showed that damping control is an effective method of control IJB, while reference 3 introduced the use of IJB for instability control and imbalance control. Reference 4 is an important contribution, showing that oil does not adversely affect the properties of AMB. It is actually shown that the oil in the AMB actually provides some small improvement to the AMB performance. Reference 5 introduces the testing of rotors on one IJB and one rolling element bearing using PID control, while reference 6 introduces fuzzy logic control into IJB, and reference 7 introduces H ∞ control into IJB and discusses load sharing between AMBs and JBs. Reference 8 introduces testing of the rotor on two IJB bearings and the ability to counteract oil film oscillation instability of the first and second modes by applying PD control. Indeed, reference 8 clearly demonstrates the success of IJB. IJB is shown to be capable of carrying high load rotors at high speeds and with the ability to control a variety of instabilities.

An off-the-shelf programmable controller was used in all of the above experiments. The control algorithms discussed in the preceding paragraphs have all been performed experimentally and have been very successful. The selection control algorithm has a choice for each application. In many cases, it is important to indicate that the magnetic bearings do not interfere with the load bearing of the JB. In fact, the H ∞ controller introduced in reference 7 actually tends to carry some of the load on the AMB, while the PD controller tends to act only as a controller. Problematically, AMBs tend to center the rotor, while JBs tend to shift the rotor center down or side to side. These two competing devices require the controller to design them to carry the load on the JB and keep all the AMB power for control. The AMB should be allowed to carry the load only in special cases (like repositioning the resonance state). The above-mentioned references provide examples of adequate controller applications. However, one skilled in the art can judiciously select an appropriate control algorithm. It should be understood that the preceding is merely a detailed description of one or more embodiments of the invention and that numerous changes to the disclosed embodiments can be made in accordance with the disclosure herein without departing from the spirit and scope of the invention. Accordingly, the foregoing description is not meant to limit the scope of the invention. Rather, the scope of the invention is to be determined solely by the appended claims and their equivalents.

Reference documents:

1) El-Shafei, a., 2010, "method of controlling instability in fluid film bearings", us patent 7,836,601.

2) El-Shafei, a. and Dimitri, a.s., 2010, "control of journal bearing instability using active magnetic bearings", ASME journal, journal of gas turbines and power engineering, volume 132, january, No. 1.

3) Dimitri, a.s. and El-Shafei, a., 2010, "instability control and imbalance compensation using magnetic bearings to support a flexible rotor on journal bearings", 8 th international conference on rotor dynamics IFToMM, september 12-15 days, KIST, seoul, korea.

4) El-Hakim, m., Dimitri, A.s, sakr, T, mahfuud, j., Adly, a.a. and EI-shamei, a., 2012, "numerical and experimental identification of combined journal-magnetic bearings: intelligent integrated bearing "record of international conference on 10 th rotational mechanical vibration, IMechE, london, UK, page 399-.

5) El-Shafei, a., Dimitri, a.s., Saqr, t. and El-Hakim, m., "test bench characterization and dynamic testing of smart electromagnetic actuator journal integrated bearings", 9 th international conference on rotor dynamics IFToMM, september 22-25 days, milan, italy, 2014. Institutional and machine science, vol 21, sprengger press.

6) Dimitri, A.S., Mahfud, J. and El-Shafei, A., 2015, "El oscillation using fuzzy controllers", journal of gas turbine Power engineering, Vol 138, No. 6.

7) Dimitri, a.s., El-Shafei, a., Adly, a.a., mahfuud, j., 2015, "magnetic actuator control of oil film oscillation instability in bearings", IEEE journal of magnetomechanical, volume 51, No. 11.

8) El-Shafei, a., Dimitri, a.s., and mahfuud, j., 2016, "PD control of smart electromagnetic actuator journal integrated bearing (IJB)" international conference on rotating machine vibration IMechE 11 th record, manchester, UK, 2016 september, document C1030, page 239-.

Claims

1. An integrated journal bearing comprising:

a shaft extending in an axial direction;

a housing through which the shaft extends in the axial direction, the housing surrounding the shaft in a radial direction;

an electromagnetic actuator arranged within the housing and surrounding the shaft in the radial direction, the electromagnetic actuator comprising a rotor lamination mounted to the shaft and an outer lamination arranged in the housing, an electromagnetic actuator radial gap being located between the rotor lamination and the outer lamination;

at least one first fluid film journal bearing disposed within the housing and surrounding the shaft in the radial direction, the first journal bearing comprising a first journal bearing sleeve mounted to the shaft axially adjacent the rotor laminations and a first journal bearing liner disposed in the housing, a first journal bearing radial gap being located between the first journal bearing sleeve and the first journal bearing liner; and is

Wherein an oil conduit is defined through the housing configured for supplying and discharging oil through the electromagnetic actuator gap and the first journal bearing gap.

2. The integrated journal bearing as in claim 1, further comprising: a second journal bearing disposed within the housing and surrounding the shaft in the radial direction, the second journal bearing comprising a second journal bearing sleeve mounted to the shaft axially adjacent a side of the rotor lamination opposite the first journal bearing sleeve, and a second journal bearing liner disposed within the housing, a second journal bearing radial gap being located between the second journal bearing sleeve and liner;

wherein the oil conduit is further configured to supply and discharge oil through the second journal bearing gap.

3. The integrated journal bearing as in claim 2, further comprising: a first retaining sleeve and a second retaining sleeve mounted axially outward from the first and second journal bearings, respectively, to the rotor.

4. The integrated journal bearing as in claim 3, further comprising: a first seal and a second seal mounted to the rotor, the first seal axially located between the first journal bearing and the first retaining sleeve, the second seal axially located between the second journal bearing and the second retaining sleeve, the first seal and the second seal configured to prevent oil from escaping between the shaft and the housing.

5. The integrated journal bearing as in claim 3, further comprising: first and second fixing adapters surrounding the first and second retaining sleeves, respectively, the first and second fixing adapters being locked in place by first and second fixing nuts, respectively.

6. The integrated journal bearing of claim 1, wherein the shaft includes a shoulder extending outward in the radial direction, a side of the rotor lamination opposite the first journal bearing sleeve being axially adjacent the shoulder.

7. The integrated journal bearing as in claim 6, further comprising: a clamp mounted to the shaft axially adjacent a side of the first journal bearing sleeve opposite the rotor laminations.

8. The integrated journal bearing as in claim 6, further comprising: a retainer sleeve mounted to the shaft, the retainer sleeve located radially between the shaft and the first journal bearing sleeve and axially adjacent to a same side of the rotor lamination as the first journal bearing sleeve.

9. The integrated journal bearing as in claim 8, further comprising: a lock nut connected to the retainer sleeve axially adjacent a side of the first journal bearing sleeve opposite the rotor laminations.

10. The integrated journal bearing as in claim 1, further comprising: a controller in signal communication with the electromagnetic actuator and configured to supply current to the electromagnetic actuator to operate the electromagnetic actuator by controlling the magnetic force generated by the electromagnetic actuator.

11. The integrated journal bearing as in claim 10, wherein the controller is configured to operate the electromagnetic actuator to carry bearing loads in addition to the journal bearing at least under some shaft conditions such that the electromagnetic actuator functions as an active magnetic bearing.

12. The integrated journal bearing of claim 11, wherein the controller is configured to receive feedback of external forces applied to the shaft at different states of the shaft and adjust the magnetic force in response to the feedback.

13. The integrated journal bearing as in claim 12, wherein the controller is configured to control the magnetic force generated by the active magnetic bearing such that the magnetic force does not interfere with the load bearing of the first journal bearing in most cases.

14. The integrated journal bearing of claim 13, wherein the controller is configured to control the magnetic force generated by the active magnetic bearing such that the active magnetic bearing provides variable and controllable stiffness and damping.

15. The integrated journal bearing as in claim 13, wherein the controller is configured to control the magnetic force generated by the active magnetic bearing such that the active magnetic bearing compensates for instability generated by the journal bearing.

16. The integrated journal bearing of claim 13, wherein the controller is configured to control the magnetic force generated by the active magnetic bearing such that the active magnetic bearing compensates for shaft imbalance.

17. The integrated journal bearing of claim 13, wherein the controller is configured to control the magnetic force generated by the active magnetic bearing such that the active magnetic bearing compensates for disturbances acting on the shaft.

18. The integrated journal bearing as in claim 1, wherein the electromagnetic actuator is configured to provide passive damping.